The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.
Decoding a previously compressed and encoded video adds a quantization error and a noise to the decoded video. The inventor(s) has experienced that the video with added quantization error and noise deteriorates the picture quality of the playback video and reduces the prediction efficiency when using the video as a reference image. Therefore, the inventor(s) has noted that using the loop filter is popular as an effective way to reduce the quantization error and noise for improving the picture quality of the playback video and to reduce the difference between the original video and the reconstructed video for increasing the prediction efficiency. The loop filter applies Wiener filters to the reconstructed video for making a sum of squared error (SSE) between the original video and reconstructed video. In order to apply the filter, the video encoding apparatus encodes filter coefficients and flags, which improves the operation efficiency.
In particular, the inventor(s) has noted that in case of inter-frame which uses previously encoded frame, the loop filter improves the efficiency of prediction and thus significantly reduces the amount of bits to be encoded and accordingly enhances the encoding efficiency.
However, the inventor(s) has experienced that in the loop filter according to the prior art, a loop filtering is performed by convoluting the Wiener filter by the unit of pixel. The inventor(s) has experienced that according to such prior art, the greater the size of the Wiener filter, the more complex the video encoding and decoding apparatuses become, and filtering a current pixel needs to use neighboring pixels.